Ultrasound imaging is widely used in medical applications to noninvasively observe structures within the human body, such as cardiac structures, the vascular system, the fetus, the uterus, the abdominal organs and the eye. In a typical imaging system, short bursts of ultrasound energy are directed into a patient's body with a handheld transducer. The returning reflected energy, or echos, are received by the same transducer. The signals representing the reflected energy are processed and formatted into a video image of the target region.
The ultrasound imaging system has a number of imaging parameters that control transmission and reception of ultrasound energy, processing of received signals and image display. Different organs and regions of the human body may require very different imaging parameters due to the different depths, sizes and tissue types of the structures being imaged. Furthermore, the ultrasound imaging system typically has several display modes for presenting different images of a target region. Examples include two-dimensional imaging, M-mode imaging, color flow imaging and Doppler imaging. For each of these display modes, various imaging parameters are adjustable. In order for an ultrasound imaging system to provide flexibility, many imaging parameters must be adjustable. Thus, adjustment of a number of imaging parameters is required to obtain a desired ultrasound image. If the imaging parameters were manually adjusted each time the instrument were used to obtain a different image, a high degree of user skill would be required. Furthermore, the manual adjustment procedure would be time consuming.
A further difficulty is that the ultrasound imaging system is typically located in a hospital where different users may operate the system at different times. Thus, a user may find the imaging system in an unknown state as a result of operation by a different user.
The problem has been partially alleviated in prior art systems by providing predetermined operating modes, such as cardiac, vascular and obstetrics. However, within each predetermined operating mode, many imaging parameters are adjustable. Thus, while use of the imaging system is simplified to some extent, adjustment for a particular exam can still be difficult and time consuming.
A further difficulty with prior art systems relates to the frequent need to perform repetitive tests. In order to obtain consistent and reliable results, the imaging system should have the same parameter settings for each test of the same type. With prior art systems, it has been difficult or impossible to return to a previous set of imaging parameters after the system has been used for a different test. The predetermined operating modes described above are insufficient for two reasons. To cover all possible imaging parameter settings would require an unacceptably large number of predetermined operating modes, many of which would be unused in any particular hospital. Second, users typically adjust imaging parameters after selection of a predetermined operating mode in order to optimize the ultrasound image.
Prior art systems typically utilize control knobs or switches wherein each parameter value is determined by the mechanical position of a control switch or adjustment knob. Storage of these values for later use is not feasible, because the stored parameter values would differ from the parameter values indicated by the control switches and adjustment knobs, and thereby cause user confusion. Several prior art systems permit storage of several parameter values for later use. However, these parameter values must be selected or typed into the system at a time when the user is unable to observe the desired ultrasound image.
A medical ultrasound imaging system which utilizes an electroluminescent touch panel is disclosed in U.S. Pat. No. 5,161,535, issued Nov. 10, 1992 to Short et al.